Tunable ferroelectric microwave bandpass filters optimised for system-level integration

Tunable bandpass filters are critical components in emerging radio frequency front-ends. A system-aware design guideline and figure of merit (FOM) are developed for optimum system-level performance. The optimisation metric discussed here deviates from earlier guidelines as the filter bandwidth is allowed to vary in the tunable range, constrained only by the downstream system analogue to digital converter. The system-aware FOM uses worst-case filter design parameters and a tuning sensitivity term that captures the frequency tunability relative to material tunability. A 6.74-8.23-GHz tunable barium strontium titanate-based filter is presented as an example to illustrate the design methodology.